In a case in which a document is read of which a special note is added with a mark using a color pen, it is required that the document is read with the added marks removed. An image processing apparatus is proposed which has a color dropout function, that is, the image processing apparatus reads a document after removing the part with a specific color contained in such a document. In this kind of image processing apparatus, for example, a two-dimensional color plane is displayed on an operation screen for the user to designate an area corresponding to a color desired to be removed (removal color) on the color plane.
However, in the use of the image processing apparatus, it is afraid that it takes a user having little knowledge relating to the color plane a lot time to set the removal color. Moreover, in a case of wanting to obtain image data of a document from which a comment originally added in the document using a color pen is removed, the user needs to adequately understand a position relationship between a position corresponding to the color of the ink of the color pen which is presented on the color plane and an area corresponding to the removal color on the color plane. If the position relationship on the color plane is not understood thoroughly and the position corresponding to the color of the ink of the color pen is deviated from the area corresponding to the removal color, it is afraid in the obtained image data of the document that the comment may not be removed as wished by the user. To remove a comment as wished by the user, the following series of operations needs to be carried out repeatedly: changing the setting on an area corresponding to the removal color on the color plane, and confirming the image data obtained by reading the document again, thus, it is time-consuming to set the removal color worriedly.